In Active-Active High Availability Direct Attached Storage (DAS) Redundant Array of Independent/Inexpensive Disks (RAID) systems, two or more controllers may issue IO requests towards the same set of virtual disks. This needs coordination and locking between the controllers. However, conventional locking mechanisms may quickly become a major overhead. Therein lies the need to provide a method and system for IO processing without the aforementioned shortcomings.